speech has not always been maintained. In fact, it has been strongly challenged—by Bolzano, for example,5 and in a certain sense even by Husserl—to the effect that even sentences expressing wishes, commands, and questions are thought to have the property of statements.
The question is still debated, and yet anyone can see that getting a clear resolution of the question is a basic presupposition  for any scientific grammar.6 Here we will not pursue the question as a matter of controversy. Instead, we will try to see whether discussing the phenomenon of truth can lead us to a foundation on which we can at least correctly pose (if not resolve) the much-debated question about the expression of objectivizing and non-objectivizing acts. Let us simply get a bit clearer on the distinction Aristotle established.
What does it mean to say that being-true and being-false are not present in an εὐχή, a request? If I say, “Please give me the scissors that are on the table,” when in fact there are no scissors on the table, what I say does not correspond with what is the case. My speech is objectively false. I am deceived, and my utterance expresses that deception. That act of speech says something false—but is my request false? Obviously not. Is it true? No, not that either. Why is it neither one nor the other? That becomes clear as soon as we really translate—i.e., interpret and express in our own language—the two Greek sentences we have quoted, in which Aristotle delineates speech qua propositional statement. Let us translate [De interpretatione, chap. 4,] 17a1.
Not all speech is indicative, i.e., shows something, but only speech in which being-true or being-false is present.
That translation fails to convey the degree of understanding that the Greeks had of that Greek sentence, due to the indeterminateness of the words “being-true” and “being-false.” When understood correctly and literally (in the strict sense of that word), the Greek word for “beingtrue”—ἀληθεύειν—means to uncover in the sense of unveiling something, removing the hiddenness from something. An adequate word for that is “to un-cover”—not in the strong sense of bringing something to light for the very first time, but in the more general sense of unveiling something that is still veiled or of again unveiling that which has again become veiled-over. In short, it means to uncover what has been covered until now, or that has become covered again. Likewise the opposite concept, ψεύδεσθαι,  does not meaning “being-false.” If we translate it that way, the meaning of the sentence remains obscure. Ψεύδεσθαι
5. See his Wissenschaftslehre, vol. 1, §22, pp. 87ff.
6. For example, unless this question is clarified, the optative and the imperative cannot be conceptually understood in contrast to the indicative.